This invention relates to an office chair in which the position of the seat is adjustable relative to the back of the chair in the forward and backward directions to accommodate users of different heights. More particularly, this invention relates to an office chair in which the position of the seat is adjustable relative to the back of the chair in the forward and backward direction, and in which the mechanism for such forward and backward adjustment does not add to the height of the seat relative to the floor.
Office chairs generally comprise a base, a seat, and a backrest. Such office chairs are mass-produced, yet must be comfortable for users of all heights and weights. This can be a challenge, because the sizes of each of the components of such office chairs are necessarily fixed. One approach to this problem has been to provide backrests that are adjustable in the vertical direction, so that they can be adjusted upwardly to accommodate taller users, and downwardly to accommodate shorter users. In this way, each user can adjust the chair backrest to obtain optimum lumbar support. Another important parameter in determining office chair comfort is adequate thigh support, as determined by the depth of the seat portion. A seat with a longer depth will provide good thigh support for a taller, longer-legged user. For a shorter user, however, the longer seat depth will maintain the user's back too far away from the backrest, so that the shorter user will slump backward when his/her back rests against the backrest. A seat with a depth of proper longitudinal dimension for a shorter user will allow the shorter user's back to engage the backrest when the user is in a proper erect posture with the feet place flat on the floor. For a taller user, however, such a seat will provide inadequate support of the user's legs, resulting in fatigue and discomfort.
It is thus one object of the invention to provide a chair in which the position of the seat is adjustable in the longitudinal direction, i.e., forwardly and rearwardly, according to the needs of the user.
It is another object of the invention to provide a chair in which the position of the seat is adjustable in the longitudinal direction by the user while the user is seated in the chair.
It is another object of the invention to provide a chair in which the position of the seat is adjustable in the longitudinal direction by the user and in which the adjustment mechanism does not add significantly to the height of the seat above the floor.